A known gas laser of this type is described in published French patent application No. 2,356,297 of Jan. 20, 1978, in the name of Battelle Memorial Institute. Said laser includes in particular: an optical resonant cavity disposed along an axis and filled with active gas; two electrodes in contact with the active gas and connected together by an induction winding and disposed on opposites sides of the axis; two capacitors each having a dielectric member and two plates, each electrode constituting a capacitor plate; and a circuit for charging the capacitors. The two electrodes are constituted by juxtaposed plates whose edges as well as the dielectric members delimit a laser passage disposed along the axis and containing the active gas. Said laser is triggered by means of a spark unit whose electrodes are connected to respective plates of the capacitors.
Such a laser has two main drawbacks.
Firstly, it is necessary to frequently adjust the distance between the electrodes of the spark unit and even to replace said electrodes. Poor reliability and short service life are the result in both cases.
Secondly, the plasma which is set up in the spark unit each time the laser is triggered is extinguished after a relatively long interval: it is therefore impossible to trigger the laser very frequently, i.e. at a frequency of more than 10 to 50 kHz in practice.
Preferred embodiments of the present invention mitigate these drawbacks and provide a gas laser in which the gas is excited by capacitor discharge, it being possible to make said laser operate at a higher triggering frequency and said laser being more reliable.